item.rb

class Item < ActiveRecord::Base
  def self.make_three_with_transactions
    transaction do
      transaction do
        Item.create!
        Item.create!
        Item.create!
      end
    end
  end
end

item_spec.rb

require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')

describe Item do
  it "should have 3 records" do
    Item.make_three_with_transactions
    Item.count.should == 3
  end

  it "should have 0 records" do
    Item.count.should == 0
  end
end